JP5045630B2 - Droplet ejector - Google Patents

Description

  The present invention relates to a droplet ejecting apparatus capable of adjusting the temperature of a jetting liquid.

  Conventionally, as a droplet ejecting apparatus, a droplet ejecting apparatus that includes a droplet ejecting head that ejects droplets toward a printing medium such as paper and prints an image, a character, a wiring pattern, or the like on the printing medium is known. Yes. The droplet ejecting head includes an energy applying member that imparts ejecting energy to the liquid stored in the head when ejecting droplets onto the print medium.

  When the liquid droplet ejecting head continuously ejects a large number of liquid droplets, for example, solid printing, heat is generated by continuously driving the energy applying member, and the liquid droplet ejecting head has heat. End up. Further, in a situation where the temperature is very low, the droplet ejecting head is cooled by the outside air while it is left without printing. In a situation where the temperature of the droplet ejecting head fluctuates greatly, the liquid temperature changes as the ejecting liquid stored in the droplet ejecting head is heated or cooled. The viscosity will change. When ejecting a liquid with a changed viscosity, the amount of ejected droplets changes compared to when ejecting droplets at normal liquid temperature, or no droplets are ejected even when ejection energy is applied. There was a problem to do.

Therefore, in order to solve such a problem, the liquid droplet ejecting apparatus described in Patent Document 1 includes an ink jet head that ejects ink as an ejecting liquid, and the stored ink is cooled inside the head. Thus, a water cooling mechanism capable of adjusting the temperature is provided. This water cooling mechanism has a partition inner groove formed inside the head and supply means for supplying a refrigerant into the partition inner groove. This inner groove is provided in the orifice plate. In the orifice plate, a nozzle capable of ejecting ink and an ink flow path communicating with the nozzle are formed. Since the orifice plate can be cooled by the coolant supplied to the groove in the partition wall, the ink in the ink flow path is efficiently cooled as compared with the case of cooling only by natural heat dissipation. Moreover, since the cooling time of the orifice plate can be adjusted by adjusting the supply time or supply amount of the refrigerant by the supply means, the ink temperature can also be adjusted.
JP 2006-7498

  The partition inner groove is separated from the ink flow path by the inner wall formed in the orifice plate, and is separated from the outside only by the outer wall formed in the orifice plate. And since the inner wall which divides an ink flow path and the outer wall which divides | segments from the exterior are formed in the substantially same thickness, there is no difference in how heat is transmitted in both. Therefore, the refrigerant in the groove in the partition wall cools the ink in the ink flow path and also cools the outside air around the orifice plate. In addition, the orifice plate is arranged with a groove in the partition opening on one surface, and a silicon substrate is bonded to the surface on which the groove in the partition opens. Therefore, the refrigerant in the groove in the partition wall comes into contact with the silicon substrate, and the silicon substrate is also cooled.

  Since the refrigerant in the groove in the partition wall described in Patent Document 1 cools not only the ink in the ink flow path but also the outside air around the orifice plate and the silicon substrate, the efficiency of cooling the ink in the ink flow path There was a problem of being bad.

  Accordingly, an object of the present invention is to suppress heat exchange with the outside air around the flow path unit as much as possible and efficiently perform heat exchange with the liquid in the liquid flow path, thereby quickly adjusting the temperature of the liquid. It is an object of the present invention to provide a liquid droplet ejecting apparatus that can be performed in the same manner.

According to a first aspect of the present invention, a liquid droplet ejecting apparatus includes a manifold plate having a common liquid chamber in which a plurality of nozzles communicate with each other, a flow path structure having a liquid flow path including the common liquid chamber, A flow path unit having a nozzle plate connected to one connection surface of the flow path structure in the thickness direction of the flow path structure and formed with the plurality of nozzles, and on the other connection surface of the flow path structure An energy applying member that is connected and applies jetting energy to the liquid in the liquid flow path for jetting droplets from the nozzle, and is formed on the manifold plate, and at least partially overlaps the nozzle plate in the thickness direction. And a supply means for supplying a circulation fluid different from the liquid in the liquid flow path to the circulation path in order to adjust the temperature of the liquid in the liquid flow path and the circulation path arranged in the region Wherein the liquid channel includes a plurality of pressure chambers connected with said common liquid chamber, and a plurality of communication passages connecting the plurality of the pressure chambers of the plurality of the nozzles, respectively, the droplets from the nozzle When jetting, the liquid flows from the common liquid chamber through the pressure chamber to the nozzle via the communication path, and the energy applying member applies jet energy to the liquid in the pressure chamber. The manifold plate is formed with the communication path, and the circulation path is arranged so as to sandwich the common liquid chamber together with the communication path in the predetermined direction. in the direction, the common liquid chamber and than the communication path is disposed near the edge faces extending in the thickness direction of the channel unit, the flow path structure, the nozzle plate and the energy Is characterized in that the higher thermal conductivity than over applying member.

  The “liquid channel” refers to a channel through which the liquid ejected from the nozzle flows. The “thickness direction” refers to a direction perpendicular to the nozzle plate connected to the flow path structure. The “connection surface” is a surface that defines the flow path structure and refers to two surfaces that intersect the thickness direction. The “energy applying member” refers to a member having a portion that applies jetting energy such as a heating resistor that applies heat or a piezoelectric material that applies pressure to the liquid in the liquid flow path. “Circulating fluid” refers to any gas or gel-like fluid that can flow in the circulation path.

According to this configuration, in the flow path structure, the nozzle plate is connected at one connection surface in the thickness direction, and the energy applying member is connected at the other connection surface. The circulation path is disposed in a region where at least a part of the circulation path overlaps with the nozzle plate in the thickness direction. Since the thermal conductivity of the flow channel structure is higher than the thermal conductivity of the nozzle plate and the energy application member, heat is more easily transmitted to the flow channel structure than the nozzle plate and the energy application member. Therefore, it is difficult for the circulating fluid to exchange heat with the outside air through the nozzle plate or the energy applying member, and exchange heat with the liquid in the liquid channel through the channel structure. It becomes easy to do. Therefore, the circulation fluid is suppressed as much as possible to exchange heat with the outside air around the flow path unit, and heat exchange is efficiently performed with the liquid in the liquid flow path. Therefore, the temperature of the liquid in the liquid channel is quickly adjusted to a predetermined temperature.
According to a second aspect of the present invention, there is provided the liquid droplet ejecting apparatus according to the first aspect , further comprising an aperture that connects the pressure chamber and the common liquid chamber and passes when the liquid flows from the common liquid chamber to the pressure chamber. The aperture and the communication path are arranged side by side in the predetermined direction, the aperture is connected to one end of the pressure chamber in the predetermined direction, and the other end of the pressure chamber in the predetermined direction The communication path is connected, and the circulation path is arranged in the vicinity of the one end of the pressure chamber .

  In the liquid droplet ejecting apparatus according to a third aspect of the present invention, in the first or second aspect, the nozzle plate is made of a resin material, the energy applying member is made of a piezoelectric material, and the nozzle plate is In the direction in which the circulation path extends and the direction orthogonal to the thickness direction, the circulation path is longer than the energy applying member.

  Since the piezoelectric material is a very expensive material compared to the resin material, the nozzle plate is made longer than the energy applying member in the orthogonal direction, so that the flow path structure on the nozzle plate side can be reduced even if the energy applying member is reduced. The energy applying member can be configured at a low cost while suppressing the escape of heat.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the energy applying member is disposed so that at least a portion thereof overlaps the circulation path in the thickness direction. It is characterized by this.

  Since the energy applying member and the nozzle plate overlap with the circulation path in the thickness direction and are connected to the flow path structure, the heat in the flow path structure is difficult to be transmitted in the thickness direction and easily transmitted in the direction perpendicular to the thickness direction. Thereby, compared with the case where an energy provision member does not overlap with a circulation path in the thickness direction, heat exchange between the circulation fluid and the liquid in the liquid channel can be performed efficiently.

Fifth droplet jetting apparatus of the present invention is directed to the first to fourth invention of any one of the channel unit has the fittable opening, before Symbol end face faces the inner wall surface of the opening A holding member that houses and holds the flow path unit in the opening, and a sealing member that is disposed in close contact with the end surface and the inner wall surface, and the sealing member is formed from the flow path structure. Is characterized by low thermal conductivity.

  The “opening” is a size that can be stored with a gap between the inner wall surface and the end surface of the flow path unit. The “sealing member” refers to a member that does not penetrate liquid in the liquid flow path regardless of liquid or solid.

  According to this configuration, the end surface of the flow path structure extending in the thickness direction is covered with the sealing member. The sealing member makes it difficult to dissipate heat from the end face of the fluid structure to the surroundings. Thereby, compared with the case where the end surface of a flow-path structure is not covered with the sealing member, it can prevent radiating from the end surface of a fluid structure to the circumference | surroundings.

  The present invention suppresses heat exchange with the outside air around the flow path unit as much as possible, and efficiently performs heat exchange with the liquid in the liquid flow path, thereby quickly adjusting the temperature of the liquid. Can do.

  Next, an embodiment of the present invention will be described. In the present embodiment, the present invention is applied to a printer that prints desired characters or images on a printing paper by ejecting ink droplets onto the printing paper from an inkjet head.

(Schematic configuration of the printer)
FIG. 1 is a perspective view illustrating a schematic configuration of a printer 1 according to the present embodiment. In addition, the up-down direction, left-right, and front-back in this specification and drawing are the up-down direction, the left-right direction, and the up-down direction orthogonal to the up-down direction and the left-right direction indicated by arrows in FIG. As shown in FIG. 1, the printer 1 includes a main body frame 2 and a conveyance roller 3 attached to the main body frame 2 and extending in the left-right direction. The main body frame 2 has a guide shaft 4 extending in the left-right direction, and the guide shaft 4 is attached to the carriage 5. The holding member 7 is attached to the lower surface of the carriage 5, and the ink jet head 6 is attached to the holding member 7.

  The carriage 5 is connected to an endless scanning belt (not shown), and the endless belt is attached to a driving shaft of a driving motor (not shown). The drive motor is disposed on the main body frame. The endless belt travels in the left-right direction as the drive shaft rotates. The carriage 5 reciprocates in the left-right direction following the traveling of the scanning belt.

(Configuration of inkjet head)
Next, the inkjet head 6 will be described in detail with reference to FIGS. 2 is a cross-sectional view of the holding member 7 and the inkjet head 6 shown in FIG. 1 cut along the line II. FIG. 3 is a cross-sectional view of the inkjet head 6 from which the holding member 7 is removed in FIG. 4 is a top view of the inkjet head 6.

As shown in FIG. 2, the carriage 5 includes an inkjet head 6 and a holding member 7. The holding member 7 has an opening 8. The opening 8 is large enough to fit the inkjet head 6 therein. The ink jet head 6 includes a flow path unit 10 including a nozzle 28 and a piezoelectric actuator 30 bonded to the upper surface 10a of the flow path unit 10. The inkjet head 6 is fitted in the opening 8, and the flow path unit 10 is held and fixed by a fixture (not shown). A potting material 9 is filled between the end face 10 z of the flow path unit 10 and the inner wall surface 7 a of the opening 8. The potting material 9 is in close contact with the end face 10z and the inner wall surface 7a, and closes the gap between the flow path unit 10 and the opening 8. This
For example, ink is prevented from leaking from the nozzles 28 during conveyance of the printer, and the ink is transmitted through the lower surface 10 b of the flow path unit 10 and enters the gap between the flow path unit 10 and the opening 8. As a result, it is possible to prevent a short circuit due to ink on the electrical components inside the carriage 5.

As shown in FIG. 3, the flow path unit 10 includes a nozzle plate 11 in which nozzles 28 are formed, and a flow path structure 12. In the flow channel structure 12, the nozzle plate 11 is connected to the lower surface 12b. The piezoelectric actuator 30 is connected to the upper surface 12 a of the flow path structure 12. The upper surface 12a of the flow channel structure 12 is also the upper surface 10a of the flow channel unit 10.

  The nozzle plate 11 is formed of a resin material such as polyimide resin. The flow channel structure 12 includes a pressure chamber plate 21, a cavity plate 22, and a manifold plate 23. The pressure chamber plate 21, the cavity plate 22, and the manifold plate 23 are made of a metal such as stainless steel. The pressure chamber plate 21, the cavity plate 22, and the manifold plate 23 are joined in a stacked state in the vertical direction.

The pressure chamber plate 21 includes a pressure chamber 26 extending in the left-right direction. The pressure chamber 26 is formed through the pressure chamber plate 21. The cavity plate 22 has an aperture hole 25 and a through hole 27a. The manifold plate 23 has a manifold 24 and a through hole 27b. As shown in FIG. 3, the manifold 24 is disposed below the pressure chamber 26 in the vertical direction. The manifold 24 is in communication with the pressure chamber 26 through an aperture hole 25 formed in the cavity plate 22. The through hole 27 a and the through hole 27 b formed in the manifold plate 23 constitute the descender 27.

The piezoelectric actuator 30 is bonded to the upper surface 21a of the pressure chamber plate 21 as shown in FIG. The piezoelectric actuator 30 includes a plurality of piezoelectric layers 31, a plurality of individual electrodes 32, a common electrode 33, and a diaphragm 34. The plurality of piezoelectric layers 31 are joined in a stacked state in the vertical direction. A plurality of individual electrodes 32 and a common electrode 33 are arranged on the piezoelectric layer 31. The individual electrode 32 is connected to a terminal 35 exposed on the upper surface 30 a of the piezoelectric actuator 30.

  The piezoelectric layer 31 is a mixed crystal of lead titanate and lead zirconate, and is made of a piezoelectric material mainly composed of lead zirconate titanate having ferroelectricity. Similarly, the diaphragm 34 is formed of a piezoelectric material. However, the diaphragm 34 is not sandwiched between the individual electrode 32 and the common electrode 33 in the vertical direction, and an electric field in the vertical direction is not generated in the diaphragm 34.

  As shown in FIG. 4, the flow path unit 10 includes a plurality of pressure chambers 26 arranged in the front-rear direction to form pressure chamber rows 26a, 26b, and the pressure chamber rows 26a, 26b are arranged in the left-right direction, respectively. Has been. The manifold 24 extends in the front-rear direction so as to overlap the plurality of pressure chambers 26. The flow path structure 10 has an ink supply port 29, and the ink supply port 29 communicates with the manifold 24. The ink supply port 29 communicates with an ink cartridge (not shown).

As shown in FIG. 4, the piezoelectric actuator 30 has a plurality of individual electrodes 32 arranged in the front-rear direction. The plurality of individual electrodes 32 are arranged corresponding to the plurality of pressure chambers 26 in plan view. The individual electrode 32 has a substantially oval shape that is slightly smaller than the pressure chamber 26, and is disposed at the center of the pressure chamber 26 in plan view. A terminal 35 is provided at the tip 32 a of the individual electrode 32. The terminal 35 is connected to a wiring member such as a flexible printed board (not shown). The flexible printed circuit board is also connected to a print control circuit (not shown), and connects the print control circuit and the individual electrode 32. The print control circuit applies a predetermined drive voltage only to the selected individual electrode 32 with respect to the plurality of individual electrodes 32. The print control circuit controls all the printing operations related to the printer 1.

  The operation principle of the piezoelectric actuator 30 having the above configuration will be described. The common electrode 33 is connected to a ground terminal (not shown) of the piezoelectric actuator 30 and has a ground potential. The individual electrode 32 to which no voltage is applied has no potential difference with the common electrode 33. When a predetermined drive voltage is applied to the individual electrode 32, a potential difference is generated between the individual electrode 32 and the common electrode 33. When a potential difference is generated between the individual electrode 32 and the common electrode 33, the vertical direction This electric field is generated in the piezoelectric layer 31. When the polarization direction of the piezoelectric layer 31 is equal to the direction of the electric field, the piezoelectric layer 31 extends in the vertical direction and contracts in the horizontal direction perpendicular to the vertical direction. Along with the contraction deformation of the piezoelectric layer 31, the vibration plate 34 is convexly deformed in the vertical direction (unimorph deformation).

  Next, the operation when the piezoelectric actuator 30 ejects ink will be described. The piezoelectric actuator 30 continues to apply a drive voltage to the individual electrode 32 in a state where ink is not ejected. For this reason, the piezoelectric layer 31 and the diaphragm 34 stand by in a state of being convexly deformed downward on the pressure chamber 26 side. When the ink is ejected, the print control circuit stops applying the drive voltage to the individual electrode 32, and accordingly, the individual electrode 32 becomes the ground potential. When the individual electrode 32 becomes the ground potential, the vibration plate 34 is deformed from the convex deformation state to a planar shape, the volume in the pressure chamber 26 is increased, and a pressure wave is generated in the pressure chamber 26. The pressure wave propagates in one direction of the pressure chamber 26 in the left-right direction. The propagated pressure wave collides with the inner wall of the pressure chamber 26 after a predetermined time, and the phase is reversed. The pressure in the pressure chamber 26 changes from a negative pressure to a positive pressure by reversing the phase of the pressure wave. Therefore, the print control circuit applies the drive potential to the individual electrode 32 again at the timing when the pressure in the pressure chamber 26 becomes positive. The pressure wave generated when the volume of the pressure chamber 26 is increased and the pressure wave generated when the diaphragm 34 is convexly deformed toward the pressure chamber 26 are combined, and the combined pressure wave is ejected onto the ink in the pressure chamber 26. Ink is ejected as energy. As a result, two pressure waves can be synthesized and applied to the ink in the pressure chamber 26, so that a much larger pressure can be applied compared to the case where one pressure wave is applied to the ink in the pressure chamber 26. .

(Configuration of circulation path and circulation mechanism)
By the way, the temperature of the ink inside the conventional inkjet head becomes non-uniform due to changes in the surrounding environment or usage conditions. The viscosity of the ink changes greatly as the temperature of the ink changes. When the viscosity changes, the flow of ink in the flow path changes, and even if jet energy is applied to the ink, it does not flow normally. Therefore, the ink jet head cannot eject ink droplets from the nozzles or cannot eject a desired ejection amount when the ink viscosity is changed. However, the conventional inkjet head does not include a temperature adjustment unit that adjusts the temperature of the ink, and the ink ejection performance cannot be adjusted due to a change in the temperature of the ink.

The ink jet head 6 of this embodiment includes a temperature adjustment unit 41 that adjusts the temperature of ink. The temperature adjustment unit 41 will be described with reference to FIGS. 3 and 4. 3 and 4, the temperature adjustment unit 41 includes a circulation path 40 formed in the manifold plate 23, a supply port 42 and a discharge port 43 formed in the circulation path 40, a circulation mechanism 44, and one end. Is a supply port 42, the other end is connected to a circulation mechanism 44, a tube 45a, one end is a discharge port 43,
The other end includes a tube 45 b connected to the circulation mechanism 44.

As shown in FIG. 3, the circulation path 40 opens to the upper surface 23 a of the manifold plate 23. The manifold plate 23 is a cavity plate 2 joined to the upper surface 23a.
2 constitutes a circulation path 40. As shown in FIG. 3, the circulation path 40 overlaps the nozzle plate 11 in the vertical direction.

  As shown in FIG. 4, the circulation path 40 extends between the outermost end of the flow path structure 10 and the outermost end of the piezoelectric actuator 30 so as to extend in the front-rear and left-right directions.

  As an example, the circulation mechanism 44 includes the configuration of the circulation mechanism described in Japanese Patent Application Laid-Open No. 2008-123488. The circulation mechanism 44 includes a circulation pump 46, a temperature adjustment unit 47, a temperature sensor 48, and a circulation control circuit 49. The circulation pump 46 supplies the circulation fluid to the supply port 42, and flows the circulation fluid discharged from the discharge port 43 into the supply port 42 again. The temperature adjusting unit 47 includes a heater that heats the circulating fluid and a cooler that cools the circulating fluid, and can heat or cool the circulating fluid. The temperature sensor 48 is mounted on the inkjet head 6 and measures the temperature of the inkjet head 6. The circulation control circuit 49 is connected to the circulation pump 46, the temperature adjustment unit 47, and the temperature sensor 48.

  Here, the control operation in which the circulation control circuit 49 controls the circulation mechanism 44 will be described. The circulation control circuit 49 estimates the temperature of the ink in the inkjet head 6 based on the temperature of the inkjet head 6 measured by the temperature sensor 48. When the circulation control circuit 49 determines that the temperature of the ink is lower than the desired temperature, the circulation control circuit 49 operates the heater provided in the temperature adjustment unit 47 to heat the circulation fluid. The circulation control circuit 49 heats the circulation fluid and drives the circulation pump 46. As a result, the heated circulation fluid flows in the circulation path 40 and warms the ink in the inkjet head 6.

  When the circulation control circuit 49 determines that the temperature of the ink is higher than the desired temperature, the circulation control circuit 49 operates the cooler provided in the temperature adjustment unit 47 to cool the circulation fluid. The circulation control circuit 49 drives the circulation pump 46 in order to flow the cooled circulation fluid to the circulation path 40. As a result, the cooled circulation fluid flows through the circulation path 40 and cools the ink in the inkjet head 6.

  The circulation fluid is not limited to a liquid such as water or a gas such as air, but may be any fluid that can be adjusted in temperature and that flows through the circulation path 40, such as a gel fluid.

  By the way, the circulation path 40 is disposed between the nozzle plate 11 and the cavity plate 22 in the vertical direction. Since the nozzle plate 11, the cavity plate 22 and the manifold plate 23 have a very thin thickness of 50 to 150 [mu] m in the vertical direction, heat is easily transferred in the vertical direction, and heat is transferred in the vertical direction and easily radiated to the outside. At the same time, the circulating fluid is warmed or cooled by the outside air. For this reason, the circulation fluid hinders the adjustment of the temperature of the ink in the inkjet head 6 and the efficiency is poor.

  The inkjet head 6 according to the present embodiment is a component of a material selected so that the thermal conductivity of each component has a certain relationship so that the circulation fluid does not easily exchange heat with the outside air. It is comprised by.

The thermal conductivity of the components constituting the inkjet head 6 will be described. FIG. 5 is a table showing the thermal conductivity of the material used for each component. The pressure chamber plate 21, the cavity plate 22, and the manifold plate 23 are formed using stainless steel. Examples of stainless steel include typical SUS403 and SUS304 used for the flow path structure 12. Both are appropriately used by the user according to the needs, and the flow path structure 12 is configured using either one of them. The nozzle plate 11 is made of polyimide resin. As for the piezoelectric actuator 30, the piezoelectric layer 31 and the diaphragm 34 are formed of lead zirconate titanate (PZT). Further, the potting material 9 shown in FIG. 2 is made of silicon resin. Note that the individual electrode 32 and the common electrode 33 arranged in the piezoelectric actuator 30 do not directly contact the pressure chamber plate 21 in the vertical direction, and thus do not affect the heat transfer from the pressure chamber plate 21.

As shown in FIG. 5, the pressure chamber plate 21, the cavity plate 22, and the manifold plate 23 have a heat conductivity of 16 [W / M · m] when made of SUS304, and a heat conductivity of 26 [W / M · m] when made of SUS430. m]. The thermal conductivity of the nozzle plate 11 is 0.29 [W / M · m]. The thermal conductivity of lead zirconate titanate, which is a material of the piezoelectric layer 31 and the diaphragm 34, is 1.5 [W / M · m] to 2.0 [W / M · m]. The thermal conductivity of the stainless steel that constitutes the pressure chamber plate 21 and the like is about 50 to 100 times larger than the thermal conductivity of the nozzle plate 11, and about 5 to 5 times that of the piezoelectric actuator 30. About 10 times larger. Since the nozzle plate 11 overlaps the circulation path 40 in the vertical direction and is joined to the flow path structure 12, the heat of the circulation fluid is hardly transmitted to the lower side on the nozzle plate 11 side. The nozzle plate 11 can also prevent the ink in the manifold 24 and the pressure chamber 26 from exchanging heat with the outside air. The piezoelectric actuator 30 does not overlap the circulation path 40 in the vertical direction, and the heat of the circulation fluid radiates from above the piezoelectric actuator 30 side. However, the piezoelectric actuator 30 is joined to the flow path structure 12 so as to overlap the manifold 24 and the pressure chamber 26 in the vertical direction. The piezoelectric actuator 30 can prevent the ink in the manifold 24 and the pressure chamber 26 from radiating heat to the outside air. This makes it difficult for the circulating fluid to exchange heat with the outside air from the nozzle plate 11 side, so that heat can be exchanged with the ink in the inkjet head 6. In addition, the ink in the manifold 24 and the pressure chamber 26 makes it difficult to exchange heat between the nozzle plate 11 and the piezoelectric actuator 30 and the outside air, and the circulation fluid and the ink in the inkjet head 6 are To be able to exchange heat efficiently.

When the inkjet head 6 is mounted on the carriage 5, as shown in FIG. 2, the potting material 9 is formed between the end surface 6 a of the inkjet head 6 in the vertical direction and the inner wall surface 7 a of the opening 8 of the holding member 7. The gap is filled. As shown in FIG. 5, the potting material 9 has a thermal conductivity of 0.2 [W / M · m], and the thermal conductivity of the stainless steel in which the pressure chamber plate 21 and the like are formed is that of the potting material 9. About 80-100 times larger than thermal conductivity. Therefore, the heat of the circulating fluid is prevented from being transmitted to the holding member 7 and the periphery of the holding member 7.

(Manufacturing / Assembly)
Next, the manufacturing method of the inkjet head 6 of this embodiment is demonstrated. The aperture hole 25 or the pressure chamber 26 is formed in the pressure chamber plate 21, the cavity plate 22 and the manifold plate 23 by a manufacturing method similar to the manufacturing method disclosed in Japanese Patent Application Laid-Open No. 2006-305948. At the time of manufacture, first, a mask pattern corresponding to the circulation path 40 is formed on the manifold plate 23 together with the manifold 24 and the through hole 27b. Next, the portion where the mask pattern is not formed is removed by etching, and the manifold 24, the through hole 27 b and the circulation path 40 are formed in the manifold plate 23. Further, the nozzle 28 is formed on the nozzle plate 11 by a manufacturing method similar to the manufacturing method disclosed in Japanese Patent Laid-Open No. 2006-305948.

The cavity plate 22 is disposed and joined so that the lower surface 21b of the pressure chamber plate 21 and the upper surface 23a of the manifold plate 23 shown in FIG. The nozzle plate 11 is joined to the lower surface 23 b of the manifold plate 23. Thereby, the flow path unit 10 is comprised. The piezoelectric actuator 30 is joined to the upper surface 21 a of the pressure chamber plate 21 after the flow path unit 10 is formed. Thereafter, the tube 45 a and the tube 45 b are connected to the supply port 42 and the discharge port 43 that open in the pressure chamber plate 21, respectively. The tubes 45a and 45b are connected to the circulation mechanism 44, respectively.

(Relationship between printing operation and circulation operation)
Next, the relationship between the printing operation of the inkjet head 6 of this embodiment and the circulation operation of the circulation mechanism 44 will be described. The circulation control circuit 49 operates when an external input device (PC or the like) connected to the printer 1 is operated or when a user issues a print command to the print control circuit by pressing a print switch provided in the printer 1. Then, the circulation mechanism 44 is driven to adjust the ink temperature before printing. Specifically, after receiving the print command, the circulation control circuit 49 confirms the temperature measured by the temperature sensor 48 and compares the ink temperature at the time of confirmation with a desired temperature. If the circulation control circuit 49 determines that the temperature of the ink at the time of confirmation is lower than the desired temperature, the circulation control circuit 49 heats the circulation fluid by the temperature adjustment unit 47 and supplies the heated circulation fluid to the circulation pump 46. To the circulation path 40. While supplying the circulation fluid to the circulation path 40, the circulation control circuit 49 confirms the temperature of the ink in the inkjet head 6. When it is confirmed that the ink temperature has reached the desired temperature, the circulation control circuit 49 stops the circulation pump 46 and also stops the temperature adjusting unit 47. Thereafter, when the circulation control circuit 49 inputs a temperature adjustment end signal to the print control circuit, the print control circuit drives the inkjet head 6 to execute a printing operation.

  When the circulation control circuit 49 determines that the temperature measured by the temperature sensor 48 is higher than the desired temperature, the circulation fluid is cooled by the temperature adjustment unit 47 and the cooled circulation fluid is removed. A circulation pump 46 supplies the circulation path 40. When the circulation control circuit 49 confirms that the ink temperature has reached the desired temperature, the circulation control circuit 49 stops the circulation pump 46 and also stops the temperature adjustment unit 47. Thereafter, when the circulation control circuit 49 inputs a temperature adjustment end signal to the control circuit, the print control circuit drives the inkjet head 6 to execute a printing operation.

(Heat exchange between circulating fluid and ink and outside air)
The heat exchange between the circulation fluid and the ink and the heat exchange between the circulation fluid and the outside air will be described with reference to FIG. FIG. 6 is an enlarged view of the periphery of the circulation path 40 including a part of the manifold 24 and the pressure chamber 26. As shown in FIG. 6, the inner wall 23 c of the manifold plate 23 exists between the circulation fluid and the manifold 24. Further, in the upward direction, a cavity plate 22 and a pressure chamber plate 21 exist between the circulation fluid and the outside air around the inkjet head 6. Furthermore, in the downward direction, the nozzle plate 11 exists between the circulating fluid and the outside air around the inkjet head 6.

  As shown in FIG. 6, when the circulating fluid exchanges heat with the ink in the manifold 24, the heat J1 of the circulating fluid is transferred to the ink in the manifold 24 via the inner wall 23 c of the manifold plate 23. It is transmitted to. The heat J2 of the circulating fluid is transmitted to the outside air through the inner wall 23d of the manifold plate 23. Heats J3 and J4 of the circulating fluid are transmitted to the outside air around the inkjet head 6 through the pressure chamber plate 21, the descender plate 22 and the nozzle plate 11. The thermal conductivity of the manifold plate 23 is about 100 times larger than that of the nozzle plate 11. Therefore, heat is more easily transmitted to the inner walls 23 c and 23 d of the manifold plate 23 than the nozzle plate 11. The heat J3 of the circulating fluid is hardly transmitted to the nozzle plate 11 side. In addition, when the potting material 9 shown in FIG. 2 is in close contact with the end face 10z of the flow path unit 10, the heat conductivity of the manifold plate 23 is about 80 to 160 times larger than that of the potting material 9, so It is difficult for J2 to be transmitted to the holding member 7 and the periphery of the holding member 7 shown in FIG. 2 through the inner wall 23d. Further, the piezoelectric actuator 30 does not overlap the circulation path 40, and the heat J4 of the circulation fluid is transmitted to the outside air via the pressure chamber plate 21 and the cavity plate 22. Therefore, it is inevitable that the heat J4 of the circulating fluid exchanges heat with the outside air around the inkjet head 6. However, since the piezoelectric actuator 30 overlaps the pressure chamber 26, it is possible to prevent ink in the pressure chamber from exchanging heat with the outside air via the piezoelectric actuator 30. Therefore, it is possible to avoid heat exchange between the circulation fluid and the outside air from the nozzle plate 11 side and the end face 10z side of the flow path unit 10 as much as possible, and the efficiency between the circulation fluid and the ink in the manifold 24 is minimized. The heat can be exchanged well.

(Function and effect)
With the printer 1 configured as described above, the following operational effects can be obtained. The ink-jet head 6 has a circulation path 40 through which a circulation fluid capable of temperature adjustment different from the ink flows. The circulation path 40 is formed in the manifold plate 23. Further, the nozzle plate 11 is laminated and joined to the manifold plate 23 so as to overlap with the entire circulation path 40 in the vertical direction. The manifold plate 23 is joined to the pressure chamber plate 21 and the cavity plate 22 in a stacked state. Then, the piezoelectric actuator 30 is joined to the pressure chamber plate 21. The thermal conductivity of the manifold plate 23 is higher than the thermal conductivity of the nozzle plate 11 and the piezoelectric actuator 30. Therefore, the heat of the circulating fluid is more easily transmitted to the manifold plate 23 than the nozzle plate 11 or the piezoelectric actuator 30. Accordingly, the heat is not easily exchanged between the circulation fluid and the outside air via the nozzle plate 11, and the heat exchange is easily performed between the circulation fluid and the ink in the manifold 24. Therefore, heat exchange between the circulating fluid and the outside air via the nozzle plate 11 is suppressed as much as possible, and heat exchange with the ink is performed efficiently. Therefore, the ink temperature can be quickly adjusted to a predetermined temperature.

  Moreover, since the end surface 10z of the flow path unit 10 is covered with the potting material 9, it is possible to suppress the heat of the circulation fluid from being transmitted from the end surface 10z to the holding member 7 and the periphery of the holding member 7.

(Correspondence between this embodiment and the present invention)
A correspondence relationship between the present embodiment and the present invention will be described. The manifold 24, the aperture hole 25, the pressure chamber 26, and the descender 27 of this embodiment shown in FIG. 3 are examples of the “liquid channel” of the present invention. The vertical direction of this embodiment corresponds to the “thickness direction” of the present invention. Further, the upper surface 12a of the flow path structure 12 and the upper surface 21a of the pressure chamber plate 21 of this embodiment are examples of “one connection surface” in the present invention. The lower surface 12b of the flow channel structure 12 and the lower surface 23b of the manifold plate 23 are examples of the “other connection surface” in the present invention. The piezoelectric actuator 30 of the present embodiment is an example of the “energy applying member” in the present invention. The front-rear direction of the present embodiment corresponds to the “direction in which the circulation path extends” in the present invention, and the left-right direction corresponds to the “perpendicular direction” in the present invention. The temperature adjustment unit 41 of the present embodiment is an example of the “supplying unit” in the present invention. The potting material 9 is an example of the “sealing member” in the present invention.

(Modification)
Next, modified embodiments in which various modifications are made to the embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.

(Modification 1)
In the above embodiment, the piezoelectric actuator 30 is configured not to overlap the circulation path 40 in the vertical direction. However, like the piezoelectric actuator 130 shown in FIG. 7, the piezoelectric actuator 130 overlaps the circulation path 40 in the vertical direction. You may comprise.

  By using the piezoelectric actuator 130, the circulation path 40 is disposed between the nozzle plate 11 and the piezoelectric actuator 130 in the vertical direction. Therefore, the heat of the circulating fluid is hardly transmitted in the vertical direction, and exchange of heat with the outside air around the inkjet head 6 can be prevented. Therefore, the circulation fluid can exchange heat with the ink more efficiently.

(Modification 2)
Further, the piezoelectric actuator 130 according to the first modification is configured to overlap with the entire circulation path 40 in the vertical direction. However, like the piezoelectric actuator 230 illustrated in FIG. 8, the piezoelectric actuator 230 overlaps only a part of the circulation path 40. You may comprise as follows.

  Since lead zirconate titanate, which is the material of the piezoelectric layer 31, is very expensive compared to resin or stainless steel, it is constructed at a low cost while preventing heat dissipation to the periphery of the inkjet head 6 by keeping it to a minimum. can do.

(Modification 3)
In the embodiment, the circulation path 40 extends linearly in the front-rear direction as shown in FIG. 4, but the circulation path 440 does not overlap with the piezoelectric actuator 30 in plan view as shown in FIG. A path 440a and a protrusion 440b connected to the main channel 440a are provided.

As shown in FIG. 9, the plurality of protrusions 440 b are disposed between the plurality of terminals 35 in the front-rear direction in plan view. Further, the protruding portion 440b is arranged to protrude toward the manifold 24 in the left-right direction. For this reason, the circulation path 440 of the present embodiment is a partition portion 2 that divides the circulation path 440 from the manifold 24 as compared with the case where the circulation path is constituted only by the main flow path 440a.
4e can be thinned. Accordingly, the heat of the circulation fluid is easily transmitted to the ink in the manifold 24 through the partition portion 24e, and therefore, compared with the case where the heat is circulated by the partition portion thicker in the left-right direction than the partition portion 24e. Fluid and ink facilitate heat exchange.

Also in the modified embodiments 1 to 3, when the inkjet head 6 is housed and held in the holding member 7, the potting material 9 is filled between the end surface 10 z of the flow path unit 10 and the inner wall surface 7 a of the opening 8. For this reason, it is possible to prevent the heat of the circulating fluid from escaping from the end face 10z of the flow path unit 10 to the periphery of the holding member 7 and the holding member 7 as in the above embodiment.

(Other changes)
Apart from the first to third modifications, a modification in which a part of the configuration of the inkjet head 6 of the present embodiment is changed is illustrated.

  The circulation path may be formed not only on the manifold plate but also on the cavity plate. The circulation path formed in the cavity plate may be formed through the cavity plate, or may be formed in a concave shape.

  The circulation control circuit may drive the circulation pump during the printing operation. For example, when printing continuously for a long time, the temperature of the ink jet head rises because the piezoelectric actuator generates heat. The circulation control circuit drives the circulation pump even during printing to cool the inkjet head. Thereby, the inkjet head is cooled, and the temperature of the inkjet head can be lowered. The circulation control circuit may be connected to a timer that measures the elapsed time since the previous printing. The circulation control circuit can change the timing for driving the circulation pump based on the elapsed time measured by the timer.

  The nozzle plate is arranged so as to overlap all the circulation paths in the vertical direction, but may be arranged so as to overlap only a part of the circulation path. Moreover, in this embodiment, although the flow-path structure illustrated what joined the several plate in the laminated state, the flow-path structure of this invention is not restricted to this. For example, the flow channel structure may be constituted by a single resin member having a liquid flow channel formed therein, or by a single plate constituting the liquid flow channel by a concave groove opening on the surface. It may be configured.

  The piezoelectric actuator 30 according to the present embodiment performs a jetting operation to stop the drive voltage applied to the individual electrode 32 by the print control circuit when jetting ink and to apply jetting energy to the ink in the pressure chamber 26. However, for example, a printing control circuit that applies a driving voltage to the individual electrodes and performs an ejection operation that imparts ejection energy to the ink in the pressure chamber is also included in the present invention.

  In the present embodiment, the fluid for circulation is a fluid different from the ink, but ink may be used.

  In this embodiment, the serial type inkjet head in which the carriage 3 reciprocates in the left-right direction along the guide shaft 5 has been described. However, for example, a line-type ink jet head that extends so as to overlap all the sheets in the left-right direction. The present invention can also be applied to an inkjet head.

  In the embodiment described above, the present invention is applied to an ink jet printer that performs printing by ejecting ink onto paper. However, the application target of the present invention is not limited to an ink jet printer. That is, the present invention can also be applied to various droplet ejecting apparatuses that eject various droplets to a target according to the application.

1 is a schematic perspective view according to an embodiment of the present invention. It is sectional drawing which cut | disconnected the holding member 7 and the inkjet head 6 which were shown in FIG. 1 according to the II line. In FIG. 2, it is sectional drawing of the inkjet head 6 except the holding member 7. In FIG. It is a top view of the inkjet head 6 of FIG. It is the table | surface which showed the thermal conductivity of the material used for each component. It is explanatory drawing for demonstrating the exchange of the heat | fever between the fluid for circulation, ink, and external air. FIG. 4 is a cross-sectional view of Modification 1 corresponding to the cross-sectional view of the inkjet head 6 shown in FIG. FIG. 4 is a cross-sectional view of a modified embodiment 2 corresponding to the cross-sectional view of the inkjet head 6 shown in FIG. 3. FIG. 4 is a cross-sectional view of a modified embodiment 3 corresponding to the cross-sectional view of the inkjet head 6 shown in FIG. 3.

DESCRIPTION OF SYMBOLS 1 Printer 3 Carriage 6 Inkjet head 7 Holding member 7a Inner wall surface 8 Opening 9 Potting material 10 Channel unit 10a End surface 11, 311 Nozzle plate 12 Channel structure 12a Upper surface 12b Lower surface 21 Pressure chamber plate 22 Cavity plate 23 Manifold plate 24 Manifold 25 Aperture hole 26 Pressure chamber 27 Descender 28 Nozzle 30, 130, 230 Piezoelectric actuator 40, 440 Circulation path 41 Temperature adjustment unit 42 Supply port 43 Discharge port 441 Protrusion path

Claims (5)

A flow path structure having a manifold plate in which a common liquid chamber communicating with a plurality of nozzles is formed, a liquid flow path including the common liquid chamber is formed, and a flow path structure in a thickness direction of the flow path structure A flow path unit having a nozzle plate connected to one connection surface of the body and formed with the plurality of nozzles;
An energy applying member that is connected to the other connection surface of the flow path structure and applies jetting energy to the liquid in the liquid flow path in order to eject liquid droplets from the nozzle;
A circulation path formed in the manifold plate and disposed in a region at least partially overlapping the nozzle plate in the thickness direction;
Supply means for supplying a circulation fluid different from the liquid in the liquid channel to the circulation channel in order to adjust the temperature of the liquid in the liquid channel;
The liquid flow path has a plurality of pressure chambers connected to the common liquid chamber, and a plurality of communication passages connecting the plurality of pressure chambers and the plurality of nozzles, respectively, and ejects droplets from the nozzles. In addition, the liquid flows from the common liquid chamber through the pressure chamber to the nozzle via the communication path,
The energy applying member is configured to apply jet energy to the liquid in the pressure chamber,
The manifold plate is formed with the communication path,
The circulation path is arranged so as to sandwich the common liquid chamber together with the communication path in the predetermined direction, and the circulation path is more in the predetermined direction than the common liquid chamber and the communication path. It is disposed near the end surface extending in the thickness direction of the unit,
The flow path structure has a higher thermal conductivity than the nozzle plate and the energy application member. An aperture that connects the pressure chamber and the common liquid chamber and through which the liquid flows from the common liquid chamber to the pressure chamber;
The aperture and the communication path are arranged side by side in the predetermined direction,
The aperture is connected to one end of the pressure chamber in the predetermined direction, and the communication path is connected to the other end of the pressure chamber in the predetermined direction,
The droplet ejecting apparatus according to claim 1, wherein the circulation path is disposed in the vicinity of the one end of the pressure chamber . The nozzle plate is made of a resin material, and the energy applying member is made of a piezoelectric material,
The droplet ejecting apparatus according to claim 1, wherein the nozzle plate is longer than the energy applying member in a direction in which the circulation path extends and a direction orthogonal to the thickness direction.   The droplet ejecting apparatus according to claim 1, wherein the energy applying member is arranged so that at least a part thereof overlaps the circulation path in the thickness direction. A holding member in which the channel unit has a fittable opening, before Symbol end face of the channel unit is housed and held to the channel unit on the inner wall surface opposed to in the opening of said opening,
A sealing member disposed in close contact with the end surface and the inner wall surface;
The droplet ejecting apparatus according to claim 1, wherein the sealing member has a thermal conductivity lower than that of the flow path structure.

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